Re: Immediate branch offset

[David Daney <ddaney.cavm@gmail.com>]

On 06/07/2013 03:34 AM, Alexis BRENON wrote:
> Hi everyone,
>
> I'm new on the list, so I'll make a short introduction of me.
> First of all, I'm french, so, please, be indulgent for my english
> mistakes...
> I'm working on the Pypy project, to create a MIPS backend (a MIPS JIT).
>
> To create the JIT, I have to load some MIPS instruction directly in
> memory without passing through a .asm file or else. So, I cannot set
> some labels. So to make some branches, I try to load the equivalent
> instruction of :
>      bne $t0, $t1, -8
> to go back, just before the bne instruction, if $t0 and $t1 are equals.
> But when it run, I've got an illegal instruction error.
> To debug, I write a small program in the MARS MIPS simulator with this
> instruction. But when compiling, assembler says me that -8 is an operand
> of incorrect type.


Dump out your program so you can disassemble it with objdump -d (or 
dissassemble it with gdb)  And verify that the code looks good.

David Daney


> I would like to know if it's possible to make a branch, with an
> immediate offset, or have I to always provide a label ?
>
> I hope my question is clear.
> Thanks for your attention, and for your answer :-p
>
> Alexis BRENON
>
> P.S. I try to go to the IRC channel, but I receive '#mipslinux :Cannot
> send to channel' every time  I send message. Is there any particular
> process to join the channel ?
>
>
>